Roof-crown for open-hearth furnaces.



T. POULL.

ROOF CRQWN FOR OPEN HEARTH FURNACES.

APPLICATION FILED JULYIB, 1916.

1,21%,066. I Patented Jan. 30,1917.

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THEODORE PO'ULL, F BIRMINGHAM, ALABAMA.

noon-snows roe oraai-nnanrn run-traces.

Application filed July 18, 1916.

To all whom it may concern:

Be it known that I, THEODORE PoULL, a citizen of the United States of America, residing at Birmingham, in the county of Jefferson and State of Alabama, have invented certain new and useful Im rovements in Roof-Crowns for 'Openearth Furnaces, of which the following is a specification.

My invention relates to a roof crownfor open hearth furnaces, and its object is to provide a crown which is movable to accommodate itself to the expansion and contraction of the furnace and which will be nomcollapsible because the crown blocks will .be so held in place that they will not fall out and interrupt the furnace operation gr necessitate repairs while the furnace is According to my invention, the crown is built oyer a wooden center in accordance with the present practice, except that it is my purpose to reduce the use of its arch to from twelve to eighteen inches so as to keep the gas closer to the bath. I provide means to positively hold the crown blocks in position, and to this end I'provide blocks which are substantially deeper than those in current use, and I provide them on each side with rabbets disposed. near their upper ends and in position to form chasesover the arch between adjoining rows of blocks. Through these chases I pass steel retaining bars which have ample clearance in the chases and are protected from the heat by strips of asbestos extending along the bottom of the chases. The rows of crown blocks at their ends bear on skew backs and the ends of the steel retaining bars rest freely on the, skew backs or like supports so that when crown expansion takes place the bars are free to move toward the center of the crown and 'when contraction takes place the crown and the bars will come back to initial position without collapse. The flat arch which my construction ows provides more head room between the crown and the buck stay girders and this enables me to increase the depth of the crown blocks, bringing their upper rabbeted ends above the skew backs so that the steel retaining bars will rest on the skew backs as the preferred supports therefor.

A further object of .my invention is to design'a crown that will stay in position so specification of Letters Patent.

Patented Jan. ac, teat...

smi no. leases.

. drawings, in which Figure 1 presents a vertical transverse section through the furnace. Fig. 2 is an enlarged vertical cross-sectional view of a portion of the crown. Fig. 3 illustrates a novel type of skew back and shows the crown blocks and a supporting bar in elevation.- Fig. t illustrates the change in position of the part when the crown is expanded, as shown in dotted lines, Fig.1.

Similar reference numerals refer to similar parts throughout the drawings.

In Fig. 1 I illustrate an open hearth steel furnace 1 having a lining of magnesite bricks 2 and silicate bricks 3 and an arched roof crown 4 of silicate brick or blocks.

The furnace is provided with buck stays 5 connected overhead to the buck stay girders 6 which have'their under'edge spaced from, and arched to correspond to, the normal arch of the roof crown when expanded. Attached to the buck stays 5 on each side'and extending longitudinally thereof from end to end of the furnace are a pair-of angle irons 7 and 8 having their horizontally disposed flanges inturned. This inturned flange of the angle 8 is fitted into the alining bottom notches9 of the row of skew backslO, and the flange of the upper angle 7 1s fitted into ,alining notches 11 at the upper outer cor- These two angles or similar devices onboth sides of the her of the row of skew backs.

furnace serve to support and hold in position the two rows of skew'backs 10 independently of the furnace lining.

- The crown blocks 12 are formed of silicate or other suitable refractory material and are made deeper and thicker than the present type of crown blocks. Preferably they extend substantially above thetop of the skew backs against which the transverse rows of crown blocks bear, being'keyed at thecenter with keys all in the manner well understood in the construction ofthe present roof crowns, except that I prefer to give my crown a minimum of rise 'as the flatter its arch the closer the gas is held to the bath.

-To prevent the blocks from falling out or vide a chase five inches in width and two inches in height extending through the. crown above the skew backs. These dimensions are given as exemplary and not as alimit to permissible design. In the chases I insert arched steel bars 14, which at their ends rest on the skew backs and on the upper angles 7 free of fixed connection to either. The ends of the bars, if desired, may be bent straight to rest flat on the top of the skew backs. Thesebars are preferably of less width than the chase'vand are of a thicknem to leave a substantial overhead clearance in the chase, thus providing for the free expansion and contraction of the bars without any tendency on their part to fracture or injure the crown blocks. To protect the bars from the furnace heat I insert in the bottom of each chase a strip of asbestos 15, preferably having the full width of the chase so that whenthe rows of blocks are assembled it will form a seal below the bar to prevent the access of heat thereto. In addition to this, the bars, due to the extra depth of the blocks, can be substantially spaced from the furnace heat. In setting in the last rows of crown blocks it is necessary to provide their respective skew backs with a wedge key section 16 which can be forced in to keep the rows in place after the blocks have been set.

In practice, the crown blocks are set over a wooden center and the initial weight and supporting strains are taken up in the same manner as with the present crowns. .As the arch expands and moves upwardly to dotted line position, Fig. 1, the steel bars 14: will also expand with the crown and their ends will move toward the center of the crown. The bars being left unattached and free to move, as seen in Fig. 4, there will be strain or binding of parts and the crown will be free to expand and contract but the retaining bars will prevent its collapse or the fallmg out of crown blocks. In the event of the fracture-of a block its under portion below the rabbets may fall out but the bar will support the upper end of the block in position so that no opening will be left in the roof, necessitating an interruption of operation and the bar being set so far up into the.

deep crown and being protected by such po-. sition and by the asbestos strip beneath itfrom the furnace heat, will not be burned out under ordinary conditions.

When it is desired to reline the furnace,

its side walls can be removed and replaced without disturbing thecrown, which will be held in position by the angle irons 7 and 8 which support the skew backs. By leaving ample space in the chases above the bars 14 for their free expansion and contraction, I

not only protect the blocks 12 from a tendency to be fractured by the bars, but I also protect the asbestos strips 15 from being unduly worn or broken by the expanding and contracting movements of the bars.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent, is

1. In an open hearth furnace, a roof crow-n formed of arched rows of crown blocks resting at their ends on skew backs, rabbets in the blocks forming arched chases between rows thereof, and floating steel reinforcing bars resting loosely in the rabbets and bearing free or fixed connection thereto on the skew backs.

2. In an open hearth furnace, a metallic frame, an arched roof crown, skew backs disposed along the sides of the furnace with their tops standing flush with a portion of the frame work and left exposed to posed along the sides of the furnace with their tops standing flush with a portion of the frame work and left exposed to form a support for reinforcing bars, said skew backs being adapted to support the roof crown, metallic reinforcing bars the ends of which rest loosely on the skew backs, and said part of the metallic frame and the arched body portions of which contact with and support the arched roof crown, and means to directly support the skew backs, by means of the metallic frame.

4.. An open hearth roof crown formed of arched rows of crown blocks resting at their ends on skew backs, the crown blocks being vertically elongated to bring their upper ends above the skew backs, rabbets in said upper ends of the crown blocks, and steel bars working loosely in the rabbets mangoes and hearing at their ends on the upper ends of the skew backs free of fixed connection thereto.

5. In an open hearth furnace, a metallic frame work comprising horizontal longitudinal angle irons, a roof crown formed of rabbeted' crown blocks, and arched steel bars extending through the rabbets and resting free of fixed connection on said angle irons to form floating supports for the roof crown that are free to follow its expansion and contraction.

6. An open hearth roof crown comprising crown blocks vertically elongated and rabbeted near their upper side walls, said rabbets forming in adjoining rows of blocks arched chases extending from side to side of the furnace, skew backs supporting the rows of blocks, and arched steel-retaining bars inserted in said chases, 'said bars having lateral and overhead clearance in the chases.

7. An open hearth roof crown comprising arched crown blocks vertically elongated and rabbeted near their upper edges, said rabbets forming arched chases extending from side to side of the furnace, means for supporting the side edges of the crown, arched steel bars inserted in said chases and having lateral and overhead clearance therein, and an asbestos strip having substantially the width and length of the chase and disposed therein below each steel bar, substantially as described.

8. In an open hearth roof crown, transverse arched rows of crown blocks having rabbets near the upper ends of their abutting faces forming chases, arched retaining bars extending through said chases and adapted each to positively prevent any adjacent crown block, as a whole from falling, skew hacks for supporting the ends of the rows of crown blocks, some of said skewv backs comprising a wedge shaped key portion, as and for the purposes described.

9. Roof crown formed of transverse arched rows of crown blocks having tapering side walls and straight end walls, there being rabbets extending transversely across the upper portion of the end walls, arched reinforcing bars, substantially wider than the depth of the rabbet, seated in and extending through the alining rabbets of adjacent rows, and projecting strips resting in the rabbets below the bars, said bars being adapted to support the top of a block in position when its lower part falls.

In testimony whereof I affix my signature.

THEODORE POULL.

Witness:

NOMIE WELSH. 

